Predictive eye saccades are different from visually triggered saccades

The metrics of eye saccades in response to random and predictable target motion were determined in 8 normal young subjects. The peak velocity of predictive saccades (PS) was significantly reduced when compared with randomly elicited saccades (RS) of equal amplitude. Saccadic gain (initial saccadic amplitude/target amplitude) was also decreased in PS. Saccadic inaccuracy was extremely frequent in PS and, in contrast to RS, it was independent of target amplitude displacement. These stimulus-dependent changes in saccadic characteristics may reflect activation of the saccadic pontine generators by different supranuclear pathways.